Conventionally, multilayer structures containing an ethylene-vinyl alcohol copolymer (hereinafter, may be referred to as EVOH) layer and a thermoplastic resin layer are molded into a film, a sheet, a cup, a tray, a bottle, and the like, and taking advantage of properties thereof, are used for various uses, such as a packaging material for foods and medicines. It is widely carried out to collect wastes, chips, and defective products generated when obtaining various molded articles from such a multilayer structure including an EVOH layer and a thermoplastic resin layer, trash after using the various molded articles, and the like and to reuse the recovery from the perspective of reduction of wastes and the economic efficiency.
However, when melt processing a recovery of a multilayer structure including an EVOH layer and a thermoplastic resin layer, there has sometimes been problems that the EVOH reacts with an adhesive resin contained in the recovery for gelation, a degraded resin adheres to a screw or a cylinder of a molding machine, or a phase separation foreign matter (hereinafter, may be referred to as die build-up) is generated at a die lip, thereby generating a burnt deposit or a fish eye or decreasing the transparency in a resin molded article obtained therefrom.
In an attempt to improve the problems, a technique is proposed that prevents generation of the die build-up by blending a resin composition containing an acid grafted polyolefin-based resin, a fatty acid metal salt, and/or a specific metal compound in a recovery (Patent Document 1). A technique is also proposed that inhibits the generation of fish eyes, the generation of die build-up, the decrease in transparency, and the like by blending a resin composition containing an acid grafted modified polyolefin-based resin and polyol in a recovery (Patent Document 2). An additive thus blended when melt kneading a recovery of a multilayer structure is called as a recycling agent. However, the present inventors have reviewed the techniques to find that the technique described in Patent Document 1 has an insufficient effect of inhibiting the generation of die build-up and the generation of fish eyes and the technique described in Patent Document 2 has an insufficient effect of improving the transparency.
In contrast, as an adhesive composition to a polar resin, such as EVOH, known is a composition mixing a ring opening polymer or condensation polymer component containing a hydroxyl group or an amino group at both ends or one end with a resin having a carboxylic acid anhydride or a derivative thereof component (Patent Document 3). However, usage of the adhesive composition as a recycling agent is not reviewed at all.